This detailed astronaut photograph depicts a portion of the Gila River channel (image center) between the Sentinel Volcanic Field and Oatman Mountain in south-central Arizona. The northernmost boundary of the Sentinel field is visible in the image, recognizable by the irregular flow fronts, or leading edge, of thin basalt lava flows erupted from low volcanic cones approximately 3.3-1.3 million years ago. The lava flow tops range in color from dark brown exposed rock to a tan, carbonate-rich soil cover. Active agricultural fields along the Gila River are a rich green set against the surrounding desert.
In contrast to the gentle topography of the Sentinel Volcanic Field, Oatman Mountain (upper left) rises from the Gila River channel to an elevation of approximately 560 meters (1,837 feet). While Oatman Mountain is located close to the Sentinel field, it represents an earlier phase of volcanic activity in the area. Volcanic rocks comprising Oatman Mountain were more viscous, leading to shorter, stronger flows that are weathered into stream channels and scarps on the mountain slopes. The mountain is a popular hang gliding destination due to abundant thermal currents rising from the surrounding desert floor and lava surfaces.